From midnight until noon, energy waxes; from noon until midnight, energy wanes.

When energy is waning, breathing exercises are of no benefit.

In other words, chee-gung should be practiced between midnight and noon, when posit-

ive Yang energy prevails in the atmosphere. Ko Hung's observation accords precisely with the findings of Western science, which has determined that the concentration of

negative ions (i.e. chee) in the air peaks between 3:00 AM and 6:00 AM. Disciplined adepts of breathing rise around 4:00 AM to take advantage of this airborne power...

By far the best hours to practice breathing are between 3:00 AM and 7:00 AM, when pos-

itive Yang energy rises most strongly in the atmosphere...

In the Orient, breathing is regarded as a science. China has its chee-gung, and India has pranayama...The essential element in air that carries the vital charge of chee {is} the negative ion - a tiny, highly active molecular fragment that carries a negative electrical charge equivalent to one electron...In polluted air, positive ions slow down, trap and neutralize the active negative ions, thereby robbing the air of vitality...The vitality of negative ions is also destroyed by air-conditioining, central heating and closed spaces.

In nature, air is naturally ionized by the action of short-wave electromagnetic radiation from the sun and by other cosmic rays, which bombard air molecules and impart vital energy to the fragments. The movement and evaporation of large bodies of water also ionize the air above them. A third method of natural ionization is the unobstructed flow of wind over wide open spaces. The most potent atmospheric chee is thus found at high altitudes where solar and cosmic radiation are strongest, winds are constant, and water takes the form of rushing streams and open lakes..."

"The Tao of Health, Sex, & Longevity" Daniel P. Reid

"The period from 12 midnight until 12 noon is called 'sheng qi' "the time of the living breath". It is best to practice {qigong} in the middle of this period, around 6 AM. The early morning is the "springtime of the day". The winter portion of the day, from noon until midnight, is called the 'si qi' "the time of the dead breath". Seeds planted in the early spring bear the healthiest fruit; those planted in the winter are less hardy. The living breath peaks at sunrise, the ideal time for qigong training. The effects of morning training are long-lasting and cumulative."